Electric vehicles such as Plug-In Electric Vehicles (PHEV), Battery Electric Vehicles (BEV) and Range Extended Electric Vehicles (REV) suffer from limited electric driving range due to the limited energy storage capacity of current electric storage and propulsion batteries (traction batteries). The use of charging leads is unpopular with users of such vehicles as they are time consuming to connect and disconnect and must be stored on the vehicle thereby taking up valuable storage space. In addition, corrosion of the plug and socket connection will increase the resistance between the plug and the socket thereby reducing charging efficiency.
Therefore in order to provide an extended driving range and simplify the recharging process, it is desirable to obviate the need to plug in a charging cord. It has therefore been proposed to use inductive charging and mount an inductive pad or inductive coupling point (VICP) to the underside of the vehicle and another fixed to the ground such that energy and information can be transferred from the fixed inductive coupling point (ICP) to the vehicle to recharge the electric battery.
Inductive charging sometimes known as “wireless charging” uses an electromagnetic field to transfer energy between two objects. Energy is sent through an inductive coupling to an electrical device (inductive coupling point), which then uses the transferred energy to charge one or more batteries on the vehicle.
An induction charger typically uses an induction coil to create an alternating electromagnetic field from within a fixed charging base station (ICP) and a second induction coil in the VICP takes power from the electromagnetic field and converts it back into electrical current to charge the battery or batteries.
A problem with such inductive coupling points is that many drivers have difficulty accurately maneuvering and positioning a vehicle onto a fixed inductive coupling point such as a fixed charging coil, especially if the charging coil is obscured by the vehicle which is the case with a ground mounted inductive coupling point (ICP).
If accurate alignment is not achieved between the fixed ICP and the VICP, large losses will result primarily due to the large air gap. These losses will result in an increased electricity cost per battery charge and also in an excessively long battery charging time.